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The electrochemical oxidation of anodic metal copper in a solution of the ligands N-[(5-tert-butyl-2-hydroxyphenyl)methylidine]-N′-tosylbenzene-1,2-diamine [H2L1] and N-[(3,5-di-tert-butyl-2-hydroxyphenyl)methylidine]-N′-tosylbenzene-1,2-diamine, [H2L2] afforded homoleptic [CuL] compounds or solvate [CuLS] complexes. The addition to the electrochemical cell of coligands (L') such as 2,2′-bipyridine (2-bpy), 4,4′-bipyridine(4-bpy) or 1,10-phenanthroline (phen) allowed the synthesis, in one step, of heteroleptic [CuLL'] compounds, namely [CuL1(H2O)] (1), [CuL1(2,2′-bpy)]⋅CH3CN (2), [CuL1(phen)]·H2O (3), [Cu2L12(4,4′-bpy)] (4), [CuL2(CH3OH)] (5), [CuL2(2,2′-bpy)] (6), [CuL2(phen)] (7) and [Cu2L22(4,4′-bpy)] (8). The crystal structures of both ligands, H2L1, H2L2, and those of the complexes (2), (4), (5), (6) and (7) have been determined by X-ray diffraction techniques. Coordination polyhedron around metal atom is square planar for [CuL2(CH3OH)] (5) and [Cu2L12(4,4′-bpy)] (4) and square pyramid for the other complexes with additional chelating ligands. The cytotoxic activity of this new series of copper(II) complexes against the SH-SY5Y neuroblastoma cell line and U87-MG and U373-MG glioblastoma cell lines has been investigated. Most of the test compounds showed higher activity than cisplatin in the three cell lines. Among this series, compound [CuL1(phen)] (3) displayed the highest activity with IC50 equal to 1.77 μM on SH-SY5Y whereas compound [Cu2L12(4.4′-bpy)] (4) resulted the most potent compounds on U87 MG and U373 MG glioblastoma cell lines. Studies on the cytotoxic activity of these derivatives suggest that these compounds induce cell death by a mechanism other than apoptosis. Xunta de Galicia Universidade de Vigo/CISUG

[EN]This study describes the synthesis of hydrotalcite-like materials by the co-precipitation method using aluminum extracted from saline slags wastes. Saline slags were chemically treated with 2 mol/dm3 aqueous solutions of NaOH for 2 h using a reflux system. The aluminum aqueous solutions were used as precursors with cobalt, magnesium and nickel nitrates, and Na2CO3, to obtain hydrotalcite-like materials with two mole M2+/Al3+ ratios, 2:1 and 4:1. The resulting solids were characterized by X-ray diffraction, termogravimetric analyses, nitrogen adsorption at −196 °C and scanning electron microscopy. After thermal treatment at 200 °C, the CO2 adsorption at 50, 100 and 200 °C was evaluated under dry conditions. The results showed a remarkable sorption capacity of 5.26 mmol/g at a pressure of 80 kPa and at a temperature of 50 °C for the MgAl-2:1 sample, with sorption capacities considerably higher than those reported in the literature for hydrotalcites under similar conditions. The Henry’s law constants were obtained directly from the adsorption isotherms at low pressures and the values found are between 0.01 and 4.20 mmol/kPa·g. The isosteric heats of CO2 adsorption found, using the Clausius-Clapeyron equation, were in the range of 5.2 to 16.8 kJ/mol., The authors are grateful for financial support from the Spanish Ministry of Economy, Industry and Competitiveness (AEI/MINECO), and the European Regional Development Fund (ERDF)

[Mn(3,5-dtSALEN)Cl] (I) and [Mn(3,5-dtSALHD)Cl] (II) complexes (3,5-dtSALEN = N,N′-bis(3,5-di-tert-butylsalicylaldehyde)ethylenediamine; 3,5-dtSALHD = N′N-bis-(3,5-di-tert-butylsalicylaldehyde)-1,2-cyclohexanediamine) were successfully encapsulated within a natural bentonite by using three preparative approaches: (A) direct adsorption of every metal complex on the previously Al-pillared bentonite, Al-PILC; (B) two-step liquid phase methodology: (i) cationic adsorption of Mn2+ in Al-PILC by substituting its residual cationic exchange capacity (CEC), followed by (ii) diffusion of either 3,5-dtSALEN or 3,5-dtSALHD ligands, for in-situ generation of the corresponding interlayered metal complexes; and (C) simultaneous pillaring/encapsulation of the complexes on the raw starting clay. The materials were characterized by cationic exchange capacity, X-ray diffraction, atomic absorption, FT-Infrared and UV–vis spectroscopies, and N2 adsorption at 77 K. The physical encapsulation of the complexes into final materials was proven by spectroscopic analyses. Method C yielded both highest metal incorporation and enhanced basal space on the modified clay. All materials showed to be active catalysts in cyclohexene epoxidation with hydrogen peroxide using acetonitrile as solvent (0.79 atm, 293 K). Addition of sodium bicarbonate as co-catalyst led to enhanced conversion (100%) and selectivity (70%) towards the epoxide in the presence of such a kind of heterogeneized metal-complex catalysts. The catalysts were stable and reusable along at least two catalytic cycles.

Natural kaolin and the metakaolin obtained by calcination of kaolin at 650 °C were chemically activated using 0.25–3.0 mol/dm3 HCl solutions. Structural and textural properties of samples were characterized by X-ray diffraction, elemental analysis and N2-adsorption/desorption analyses. The amount of Bronsted acid sites (BAS) was determined by infrared spectroscopy using pyridine as probe molecule. The amount of BAS for kaolin rose with increasing HCl concentration up to 1.0 M, and decreased for higher concentrations, that is related with the leaching of Al from the solid. Effect of HCl concentration on amount of BAS was negligible for metakaolin. The catalytic performance of these materials was investigated in the Prins cyclization of (−)-isopulegol with vanillin to form octahydro-2H-chromen-4-ol, carried out in toluene at 50 °C. The reaction rate and the selectivity toward octahydro-2H-chromen-4-ol depended on the Bronsted acidity, structural and textural properties of the catalysts. The reaction rate in the presence of kaolin modified by HCl correlated with the amount of BAS. HCl-kaolin samples were more active compared with HCl-metakaolin, while selectivity reaction toward octahydro-2H-chromen-4-ol was larger in the presence of HCl-metakaolin.

Producción Científica, This manuscript reports the synthesis and liquid crystal behavior of isocyanoazulene gold(I) complexes [AuX (CN-Az)] (Az = azulene; X = halide, perhalophenyl or alkynyl) and [μ-4,4′-C6F4C6F4{Au(CN-Az)}2]. The comparison of the X-ray structures of homologous compounds, reveals that the introduction of a long substituent in the system produces a loss of molecular planarity that induces a decrease in the melting temperatures. The free 2-isocyanoazulene is not a liquid crystal itself, but its gold complexes bearing a C10 hydrocarbon chain display a SmA mesophase, whose formation is driven by nanosegregation between molten chains and aromatic parts. The free isocyanide is strongly colored and displays fluorescence in solution associated with the azulene fragment, which is largely diminished upon coordination to the gold fragment., Ministerio de Ciencia, Innovación y Universidades (Project CTQ2017-89217-P), Junta de Castilla y León (Project VA038G18)

The Prins cyclization of (−)-isopulegol with vanillin to form octahydro-2 H -chromen-4-ol was studied in the presence of natural layered aluminosilicates modified by 0.5 mol/dm 3 HCl, such as montmorillonite, kaolin, and metakaolin obtained by the calcination of kaolin at 650 °C. According to infrared spectroscopy using pyridine as probe molecule, the amount and strength of Bronsted acid sites depend on the type of clay and decrease in the following order HCl-montmorillonite > HCl-kaolin > HCl-metakaolin. The difference in Bronsted acidity and textural properties of clays affected the reaction rate and the selectivity towards octahydro-2 H -chromen-4-ol.

Catalytic wet peroxide oxidation (CWPO) with an Al/Fe-pillared clay catalyst was assessed in the treatment of stabilized leachate of landfill (COD = 5000–7000 mg O 2 /dm 3 ; BOD 5 ∼ 800 mg O 2 /dm 3 ; pH = 8.0; BOD 5 /COD = 0.11–0.16). The effects of catalyst loading ( 0.5 – 2.0 g catalyst / 100 c m leachate 3 ), added peroxide concentration (2.34–4.68 mol/dm 3 ) and its rate of stepwise addition (7.5–30 cm 3 /h) in a semi-batch reactor, were studied with COD removal and biodegradability index (BI) 1 as response parameters. COD removals up to 50% and BI output values exceeding 0.3 were achieved in 4 h of reaction at very mild conditions of room temperature and atmospheric pressure (291 K; 72 kPa). High catalyst loadings together with low peroxide concentrations and dosages (below stoichiometric for total mineralization) and low peroxide addition rates were found to provide better use of the oxidizing agent in terms of both, BI enhancement and COD removal. The clay catalyst resulted quite stable against the chemical leaching of the active iron along the catalytic reactions.

Saponites containing divalent Mg, Ni, or Fe as octahedral cations and trivalent Al and Fe substituting Si in the tetrahedral sheet were synthesized using microwave radiation. Saponite with a high specific surface area was obtained in all the syntheses, although Fe-Al saponite crystallized was impurified by Fe2O3 and analcime. The catalytic activity of the solids for the epoxidation of (Z)-cyclooctene by hydrogen peroxide was tested, the solids obtained being highly active (conversion up to 8.8%, and 100% selectivity to the epoxide).